I'd recommend Roundstone Resort in Weatherly. It's a private property. It's not really that big: 3 cabins and 5 tent sites. I'm not sure if they allow RVs though. It's a bit primitive, but if you're looking for a cozy place to stay that's quiet, you should try it. Here's their website if you wanna check it out further: http://www.campingatroundstone.com/

Are you looking for a campground for RVs, tent camping or cabin camping?

Since you're planning to head over to the Boston area, I'd recommend trying out the Boston/Cape Cod KOA. They got really great sites and a load of facilities for you and the family. They also got some cabins for you. It's also close to the Plimoth plantation, and other historic sites. It's also close to Cape Cod so you can enjoy the beaches. I believe they also got access to bring you to Martha's Vineyard and Nantucket Island as well.